1. Field of the Invention
The present invention relates to a system for selectably elevating a coiled tubing injector or tensioner from a first stowed position on the deck of a transport trailer or in a second position resting on an elevated rig floor of a drilling rig. The system uses lifting lines from the mast to raise the coiled tubing tensioner from the first position to the second position.
2. Description of the Related Art
Coiled tubing rigs primarily include a tubing storage reel and a coiled tubing injector or tensioner for forcing a string of coiled tubing into or pulling it out of a well. Coiled tubing rigs are commonly used in the oilfield for reasons of speed and low cost operation.
Due to advances in the ability to run downhole drilling motors on the lower end of a coiled tubing drill string, a need has arisen for coiled tubing injectors or tensioners which can be positioned on a rig floor so that the tubing from the injector is coaxially aligned with the well bore. Previously, this need has been filled by lifting a self-contained conventional tensioner from a transport trailer to the rig floor using large forklift trucks, cranes, or other means. Upon completion of a job by such a tensioner, the tensioner has to be lifted back onto the transport trailer.
Alternatively, as described in U.S. Pat. No. 7,708,058, the tensioner may be lifted from a trailer to the drilling rig floor with the use of large hydraulic cylinders.
When being transported, such a conventional tensioner must be restrained by tiedown means, so the conventional approach involves considerable setup and rig down time, as well as necessitating lifting equipment. Additionally, the storage reel must be carefully positioned during the lifting to and from the rig floor in order to avoid damaging the tubing, particularly when the tubing is left engaged with the injector. If the tubing is released from the injector for lifting, then it must be rethreaded through the injector after the injector has been lifted.
Accordingly, a need exists for a system to readily reposition a coiled tubing injector or tensioner between a transport trailer and a rig floor.